Lytic spondylolisthesis usually occurs at L5/S1 and normally presents in the teenage years or 20s. The classical example is the so-called fast (cricket) bowler’s “stress fracture”. It occurs due to repetitive stresses in the lumbar spine but it often appears with no obvious history of repetitive trauma.
Spondylolisthesis simply means the abnormal slip of one vertebra with respect to the vertebra immediately below. This is usually occurs forwards (anteriorly) of the upper vertebra, also known as anterolisthesis. Less common is a backwards (posterior) slip, also known as retrolisthesis. Much less common is a sideways (lateral) slip, called a laterolisthesis.
Usually in degenerative or traumatic spondylolisthesis, decompression of the neural elements, both centrally and laterally, over the nerve roots is indicated. Optimal decompression is usually achieved through a posterior laminectomy and total facetectomy with radical decompression of the nerve root (ie, Gill procedure).
Ikuta K, Tono O and Oga M: Clinicaloutcome of microendoscopic posterior decompression for spinalstenosis associated with degenerative spondylolisthesis - minimum2-year outcome of 37 patients. Minim Invas Neurosurg. 51:267–271.2008.
Although technology continues to improve the performance of surgical treatment, the most challenging task is simply optimal patient selection. As stated previously, clear indications for fusion must be present in order to optimize outcome, and controversies still exist, especially in the treatment of degenerative spondylolisthesis, that must be resolved in a methodic and scientific manner. Prospective randomized studies with independent evaluators probably will produce the greatest improvement to the outcome of lumbar fusions.
Spondylolisthesis refers to the forward slippage of one vertebral body with respect to the one beneath it. This most commonly occurs at the lumbosacral junction with L5 slipping over S1, but it can occur at higher levels as well. It is classified on the basis of etiology into the following five types :
Spondylolysis relates to instability of specific bones in the low back. It a very common cause of back pain, particularly in adolescents. Gymnasts who perform routines that bend and arch the back are often victims of spondylolysis or spondylolisthesis.
Spondylolysis and spondylolisthesis are conditions affecting the joints that align the vertebrae one on top of the other. Spondylolysis is a weakness or stress fracture in the facet joint area. This weakness can cause the bones to slip forward out of normal position, called spondylolisthesis, and kink the spinal nerves. Treatment options include physical therapy to strengthen the muscles. A back brace may be used to support the spine. In some cases, surgery can realign and fuse the bones.
The pars interarticularis, or isthmus, resists significant forces during normal motion. The pars may be congenitally defective (isthmic spondylolisthesis as spondylolysis) or may undergo repeated stress under hyperflexion and rotation that results in microfractures. Lumbar lordosis, gravity, posture, high-intensity activities (eg, gymnastics), and genetic factors all play a role in slip development. If a fibrous nonunion forms from an ongoing insult, elongation of the pars and progressive listhesis results; this is observed in another subtype of type 2 (isthmic) spondylolisthesis. In persons with spondylolysis, 30-50% are believed to progress to spondylolisthesis. The most common location is at L5-S1.
Mild cases of spondylolysis and spondylolisthesis usually cause minimal pain. In fact, the conditions are often found by accident when a person has a pre-employment exam or an X-ray of the back for an unrelated reason.
The pars interarticularis, or isthmus, is the bone between the lamina, pedicle, articular facets, and the transverse process. This portion of the vertebra can resist significant forces during normal motion. The pars may be congenitally defective (eg, in spondylolytic subtype of isthmic spondylolisthesis) or undergo repeated stress under hyperextension and rotation, resulting in microfractures. If a fibrous nonunion forms from ongoing insult, elongation of the pars and progressive listhesis results. This occurs in the second and third subtypes of type 2 (isthmic) spondylolisthesis. These typically present in the teenage or early adulthood years and are most common at L5-S1.
With aging of the population, degenerative lumbarspinal stenosis (DLSS) is becoming an increasingly common spinaldisease. DLSS is often characterized by radiological findings ofmultilevel disc herniation and lumbar spondylolisthesis and isdifficult to treat. Although there has been a series ofimprovements in surgical technique, the traditional laminectomywith interbody or posterolateral fusion from the posterior approachcontinues to be widely used. However, multilevel fusion causesgreat damage to the normal structure, prolongs recovery time andmay result in chronic lower back pain (). In the current study, we evaluated thecombined use of microendoscopic discectomy (MED) and minimallyinvasive transforaminal lumbar interbody fusion (MI-TLIF) for thetreatment of multilevel DLSS with spondylolisthesis, which hadsatisfactory short-term clinical outcomes, and compared thecombined surgery with the traditional lumbar interbody fusion fromthe posterior midline approach (PLIF).
Pathologic spondylolisthesis results from generalized bone disease, which causes abnormal mineralization, remodeling, and attenuation of the posterior elements leading to the slip.